Tees And Offtakes Landing

Mill-Pro offers a wide range of injection moulded and fabricated tee pieces in both Blue and Black including:

  • Moulded Electrofusion Tees 
  • Moulded Spigot Tees 
  • Electrofusion Saddles
  • Fabricated Tees  

Injection moulded Electrofusion Tees are used for smaller diameter pipelines (≤ 315 OD). Moulded in a single shot and in both equal and reducing offtakes.  They do not contain angled butt welds and do not require de-ration. 

Injection moulded Spigot Tees are available in larger sizes up to DN/OD 450 SDR11, however generally not listed for water supply as the Minimum Order Quantity (MOQ) makes sizes > dn315 uneconomic.  We recommend using fabricated tees, however, a list of larger size black moulded spigot tees can be found in our wastewater section here

Electrofusion saddles are not covered under the WSD PS and are generally not used in Hong Kong unless special approval is provided.  Saddles are ideal to conduct live cut-ins to existing PE pipelines and install air valves in locations where clearance above the pipe crown is limited. 

Fabricated Tees in sizes from dn355 are manufactured by CNC machining a 'Fitting Body' from extruded hollow PE bar then pipe spigots are factory butt-welded on.  The required tee reinforcement is incorporated directly into the fitting body during machining, therefore they do not require de-ration (see Fig.1 below). Any custom tee design can be made in any size, including reducing, scour and angled off takes.  Fabricated tees are ideal for use in valve and pump chambers, where unique one-off components can be manufactured, eliminating Ductile Iron fittings to reduce long term maintenance.

Note: The specifications for fabrication and type testing for the supply of fabricated fittings to ensure their performance, are given in the Hong Kong Water Supplies Department, WSD Appendix 22.09, Clause 5.5.7.

Segmented Tees are prohibited in the Hong Kong Water Supplies Department (WSD) network. WSD Particular Specification PS22.09, Clause 5.5.6 prohibits the use of segmented tees.  A segmented Tee is manufactured by cutting PE pipe at a 45º angle and butt welding the pipe segments together (described in BS EN 12201-3 Annex B5). Refer fabricated bends Fig.2 for a more detailed explanation of de-ration). According to BS EN 12210-3 Annex A, Figure B.4 A segmented Tee fabricated from PN16 pipe must have a de-rating factor of 0.6x (60%) applied to the original pipes PN rating, so a segmented tee fabricated from PN16 pipe must be derated to PN9.6, this makes segmented tee's unusable in a PN16 water network.

Fig. 1 - Manufacturing process for fabricated fittings

As the design options for fabricated fittings are unlimited, it's not possible to provide tables on every option available.  However, sizes up to DN700 are shown in accordance with the WSD PS and sizes up to DN/OD 2000 are available.  For more information on fabricated fitting designs not shown contact us to assist with your requirements.

Photo credits: Reinert-Ritz world leaders in the manufacture of fabricated PE fittings for water and wastewater.

Click below, to see complex design and rehabilitation solutions delivered using large diameter fabricated PE fittings. Reinert-Ritz.pdf